/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "flutter/sky/engine/core/rendering/style/ShadowList.h"

#include "flutter/sky/engine/platform/geometry/FloatRect.h"
#include "flutter/sky/engine/wtf/OwnPtr.h"

namespace blink {

static inline void calculateShadowExtent(const ShadowList* shadowList,
                                         float& shadowLeft,
                                         float& shadowRight,
                                         float& shadowTop,
                                         float& shadowBottom) {
  ASSERT(shadowList);
  size_t shadowCount = shadowList->shadows().size();
  for (size_t i = 0; i < shadowCount; ++i) {
    const ShadowData& shadow = shadowList->shadows()[i];
    if (shadow.style() == Inset)
      continue;
    float blurAndSpread = shadow.blur() + shadow.spread();
    shadowLeft = std::min(shadow.x() - blurAndSpread, shadowLeft);
    shadowRight = std::max(shadow.x() + blurAndSpread, shadowRight);
    shadowTop = std::min(shadow.y() - blurAndSpread, shadowTop);
    shadowBottom = std::max(shadow.y() + blurAndSpread, shadowBottom);
  }
}

void ShadowList::adjustRectForShadow(LayoutRect& rect) const {
  FloatRect floatRect(rect);
  adjustRectForShadow(floatRect);
  rect = LayoutRect(floatRect);
}

void ShadowList::adjustRectForShadow(FloatRect& rect) const {
  float shadowLeft = 0;
  float shadowRight = 0;
  float shadowTop = 0;
  float shadowBottom = 0;
  calculateShadowExtent(this, shadowLeft, shadowRight, shadowTop, shadowBottom);

  rect.move(shadowLeft, shadowTop);
  rect.setWidth(rect.width() - shadowLeft + shadowRight);
  rect.setHeight(rect.height() - shadowTop + shadowBottom);
}

PassRefPtr<ShadowList> ShadowList::blend(const ShadowList* from,
                                         const ShadowList* to,
                                         double progress) {
  size_t fromLength = from ? from->shadows().size() : 0;
  size_t toLength = to ? to->shadows().size() : 0;
  if (!fromLength && !toLength)
    return nullptr;

  ShadowDataVector shadows;

  DEFINE_STATIC_LOCAL(ShadowData, defaultShadowData,
                      (FloatPoint(), 0, 0, Normal, Color::transparent));
  DEFINE_STATIC_LOCAL(ShadowData, defaultInsetShadowData,
                      (FloatPoint(), 0, 0, Inset, Color::transparent));

  size_t maxLength = std::max(fromLength, toLength);
  for (size_t i = 0; i < maxLength; ++i) {
    const ShadowData* fromShadow = i < fromLength ? &from->shadows()[i] : 0;
    const ShadowData* toShadow = i < toLength ? &to->shadows()[i] : 0;
    if (!fromShadow)
      fromShadow = toShadow->style() == Inset ? &defaultInsetShadowData
                                              : &defaultShadowData;
    else if (!toShadow)
      toShadow = fromShadow->style() == Inset ? &defaultInsetShadowData
                                              : &defaultShadowData;
    shadows.append(toShadow->blend(*fromShadow, progress));
  }

  return ShadowList::adopt(shadows);
}

PassOwnPtr<DrawLooperBuilder> ShadowList::createDrawLooper(
    DrawLooperBuilder::ShadowAlphaMode alphaMode) const {
  OwnPtr<DrawLooperBuilder> drawLooperBuilder = DrawLooperBuilder::create();
  for (size_t i = shadows().size(); i--;) {
    const ShadowData& shadow = shadows()[i];
    drawLooperBuilder->addShadow(
        FloatSize(shadow.x(), shadow.y()), shadow.blur(), shadow.color(),
        DrawLooperBuilder::ShadowRespectsTransforms, alphaMode);
  }
  drawLooperBuilder->addUnmodifiedContent();
  return drawLooperBuilder.release();
}

}  // namespace blink
